The present invention relates to an electrolytic capacitor which can be rapidly charged and discharged with electric charge of high voltage and large capacity, and more particularly to an electrolytic capacitor used as an auxiliary power source for cars or other vehicles which use fuel cells as a power source.
In recent years, development of fuel cell vehicles (FC vehicles) is very rapid. A fuel cell for the FC vehicles is supplied with high-pressure hydrogen as fuel and is used as a power source replacing a gasoline engine. This FC vehicle uses the DC electric power which is generated by the fuel cell, and drives DC motors directly. Thus, it attracts attention all over the world as a most efficient power source. In such an FC vehicle, a system using an electrolytic capacitor of a large capacity as a source of auxiliary power is proposed in order to supplement a large power required at the time of the start of vehicles. The electrolytic capacitor of a large capacity is charged with an electric power from the fuel cell while the vehicle is running and is charged with an electric energy converted from a kinetic energy recovered at the time of braking. The electric power thus charged is discharged from the electrolytic capacitor and is supplied to the DC motor together with the electric power from a fuel cell at the time of the start of vehicles.
However, few of the conventional electrolytic capacitors instanteneously discharge the charges stored, because they have an ion conduction structure. That is, generally, conventional electrolytic capacitors need a long time for charging and discharging. Instantaneous movement of a large electric charge gives strong ion bombardment against the cathode. As a result, heat and a lot of hydrogen gas are generated from a surface of the cathode, which shortens the life of the capacitor remarkably. Furthermore, there are still many room of improvements in a withstand voltage of the electrolytic capacitors, because few of conventional ones have a withstand voltage of exceeding 500 V.
Therefore, it is an object of the present invention to provide a new electrolytic capacitor having charge and discharge characteristics of a high voltage and a high capacitance, which is indispensable for the capacitor used for an auxiliary power supply of a fuel cell.
It is another object of the present invention to provide an electrolytic capacitor, which realizes higher moving speed of internal electrons during charging and discharging than any of conventional electrolytic capacitors.
It is yet other object of the present invention to provide an electrolytic capacitor, in which there is no ion bombardment against the cathode at the time of instantaneous movement of a large electric charge and which enables a high speed storing of the electric charge recovered.